Body fluid sampling device and methods of use

ABSTRACT

A device for sampling body fluid includes a housing having a sleeve at a forward end thereof which is displaceable in response to being pressed against a user&#39;s skin to trigger the firing of a lancer. After the lancet is removed from the incision, the sleeve is repeatedly pressed against the skin to depress a ring of body tissue in surrounding relationship to the incision to express body fluid outwardly through the incision. A pusher member is then actuated to push a capillary tube through a front end of the housing for drawing-in body fluid. The lancet is a disposable lancet which includes a body supporting a skin-lancing member and the capillary tube. The disposable lancet passes through an upper end of a lancet carrier when being installed or removed. The device cannot be armed until the disposable lancet is installed in the housing, because the capillary tube functions to push a safety device to a non-safety position.

PRIOR APPLICATIONS

This application claims benefit of provisional applications Ser. No.60/017,133 filed May 17, 1996; 60/019,918 filed Jun. 14, 1996;60/023,658 filed Aug. 1, 1996; 60/025,340 filed Sep. 3, 1996; 60/714,548filed Sep. 16, 1996; and 60/710,456 filed Sep. 17, 1996; the disclosuresof which are incorporated herein by reference.

The present invention is related to inventions disclosed in thefollowing concurrently filed, commonly assigned U.S. applications: Ser.No. 08/858,045, entitled "Methods and Apparatus For Sampling Body Fluid"(attorney docket no. 018176-057); Ser. No. 08/857,335, entitled"Disposable Element for Use in a Body Fluid Sampling Device" (attorneydocket 018176-058); Ser. No. 08/858,042 entitled "Methods and Apparatusfor Sampling and Analyzing Body Fluid" (attorney docket 018176-059);Ser. No. 08/858,043, entitled "Methods and Apparatus For Expressing BodyFluid from an Incision" (attorney docket 018176-060) and Ser. No.08/975,978 entitled "Body Fluid Sampling Device". The disclosures ofthose applications are incorporated herein by reference.

1. Field of the Invention

The present invention relates to lancing devices and methods forobtaining samples of blood and other fluids from the body for analysisor processing.

2. Background of the Invention

Many medical procedures in use today require a relatively small sampleof blood, in the range 5-50 μL. It is more cost effective and lesstraumatic to the patient to obtain such a sample by lancing or piercingthe skin at a selected location, such as the finger, to enable thecollection of 1 or 2 drops of blood, than by using a phlebotomist todraw a tube of venous blood. With the advent of home use tests such asself monitoring of blood glucose, there is a requirement for a simpleprocedure which can be performed in any setting by a person needing totest.

Lancets in conventional use generally have a rigid body and sterileneedle which protrudes from one end. The lancet may be used to piercethe skin, thereby enabling the collection of a blood sample from theopening created. The blood is transferred to a test device or collectiondevice. Blood is most commonly taken from the fingertips, where thesupply is generally excellent. However, the nerve density in this regioncauses significant pain in many patients. Sampling of alternate sites,such as earlobes and limbs, is sometimes practiced to access sites whichare less sensitive. These sites are also less likely to provideexcellent blood samples and make blood transfer directly to test devicesdifficult.

Repeated lancing in limited surfaces areas (such as fingertips) resultsin callous formation. This leads to increased difficulty in drawingblood and increased pain.

To reduce the anxiety of piercing the skin and the associated pain, manyspring loaded devices have been developed. The following two patents arerepresentative of the devices which were developed in the 1980's for usewith home diagnostic test products.

Cornell et al. U.S. Pat. No. 4,503,856 describes a spring loaded lancetinjector. The reusable device interfaces with a disposable lancet. Thelancet holder may be latched in a retracted position. When the usercontacts a release, a spring causes the lancet to pierce the skin athigh speed and then retract. The speed is important to reduce the painassociated with the puncture.

Levin et al. U.S. Pat. No. 4,517,978 describes a blood samplinginstrument. This device, which is also spring loaded, uses a standarddisposable lancet. The design enables easy and accurate positioningagainst a fingertip so the impact site can be readily determined. Afterthe lancet pierces the skin, a bounce back spring retracts the lancet toa safe position within the device.

In institutional settings, it is often desirable to collect the samplefrom the patient and then introduce the sample to a test device in acontrolled fashion. Some blood glucose monitoring systems, for example,require that the blood sample be applied to a test device which is incontact with a test instrument. In such situations, bringing the fingerof a patient directly to the test device poses some risk ofcontamination from blood of a previous patient. With such systems,particularly in hospital settings, it is common to lance a patient,collect a sample in a micropipette via capillary action and then deliverthe sample from the pipette to the test device.

Haynes U.S. Pat. No. 4,920,977 describes a blood collection assemblywith lancet and microcollection tube. The device incorporates a lancetand collection container in a single device. The lancing and collectionare two separate activities, but the device is a convenient singledisposable unit for situations when sample collection prior to use isdesirable. Similar devices are disclosed in Sarrine U.S. Pat. No.4,360,016, and O'Brien U.S. Pat. No. 4,924,879.

Jordan et al. U.S. Pat. No. 4,850,973 and U.S. Pat. No. 4,858,607,disclose a combination device which may be alternatively used as asyringe-type injection device and a lancing device with disposable solidneedle lancet, depending on configuration.

Lange et al. U.S. Pat. No. 5,318,584 describes a blood lancet device forwithdrawing blood for diagnostic purposes. This invention uses arotary/sliding transmission system to reduce the pain of lancing. Thepuncture depth is easily and precisely adjustable by the user.

Suzuki et al. U.S. Pat. No. 5,368,047, Dombrowski U.S. Pat. No.4,653,513 and Ishibashi et al. U.S. Pat. No. 5,320,607 each describesuction-type blood samplers. These devices develop suction between thelancing site and the end of the device when the lancet holding mechanismwithdraws after piercing the skin. A flexible gasket around the end ofthe device helps seal the end around the puncture site until adequatesample is drawn from the puncture site or the user pulls back on thedevice.

Garcia et al. U.S. Pat. No. 4,637,403 and Haber et al. U.S. Pat. No.5,217,480, disclose combination lancing and blood collection deviceswhich use a diaphragm to create a vacuum over the wound site.

Erickson et al. U.S. Pat. No. 5,582,184 describes a means of collectingand measuring body fluids. This system uses a coaxial syringe andcapillary tube disposed within a spacer member. The spacer member limitsthe depth of springe penetration and compresses body tissue around thesyringe while the syringe is in the skin, for improving the flow ofinterstitial fluid to the incision. However, it will be appreciated thatthe incision will tend to close against the syringe, thereby limitingany advantage that can be achieved.

Single use devices have also been developed for single use tests, i.e.home cholesterol testing, and for institutional use to eliminatecross-patient contamination multi-patient use. Crossman et al. U.S. Pat.No. 4,869,249, and Swierczek U.S. Pat. No. 5,402,798, also disclosedisposable, single use lancing devices.

U.S. Pat. Nos. 5,421,816; 5,445,611; and 5,458,140 disclose, as areplacement for invasive sampling, the use of ultrasound to act as apump for expressing interstitial fluid directly through intact(non-lanced) skin. The amount of fluid which can be obtained in that wayis very limited, however.

The disclosures of the above patents are incorporated herein byreference.

Even with the many improvements which have been made, the painassociated with lancing remains a significant issue for many patients.The need for blood sampling and the fear of the associated pain is alsoa major obstacle for the millions of diagnosed diabetics, who do notadequately monitor their blood glucose due to the pain involved.Moreover, lancing to obtain a blood sample for other diagnosticapplications is becoming more commonplace, and less painful, minimallyinvasive device is needed to enhance those applications and make thosetechnologies more acceptable.

An object of the present invention therefore, is to provide a device anda method for obtaining a sample of bodily fluid through the skin whichis virtually pain free and minimally invasive.

Furthermore, known lancing devices include manually actuable buttons fortriggering the lance-driving mechanism once the user has placed thedevice against his/her skin. Because the user knows the precise instantwhen the lancet will be triggered, there is a tendency for the user tojerk or raise the device at the instant of triggering, which can lead toinconsistent skin penetration, or possibly no penetration. Therefore, afurther object of the invention is to provide a lancing device whicheliminates such a tendency on the part of the user.

Moreover, known carriers for supporting disposable lancets areconfigured to permit the disposable lancet member to be inserted andremoved solely through a lower end thereof. That requires that a usergrasp a lower portion of the disposable lancet member in order to pushit upwardly or pull it downwardly. Since the needle projects from alower end of the disposable lancet member the user's hand will be in theimmediate vicinity of the needle, and thus exposed to potential injuryand/or contamination. Also, the disposable lancet member is typicallyheld in the carrier by friction fit. Due to normal manufacturingtolerances, it is difficult to ensure a sufficiently tight fit for thedisposable lancet member; there may be a tendency for the disposablelancet member to wobble, thereby increasing the amount of pain inflictedduring a lancing step.

Therefore, it is another object of the invention to provide a lancetcarrier which eliminates the above-mentioned shortcomings.

An additional object of the invention is to make a lancing device saferby preventing the lancet-driving mechanism from being cocked until thedisposable has been inserted therein.

Another object of this invention is to provide a method which can resultin a sample of either blood or interstitial fluid, depending on thesample site and the penetration depth utilized. While there are nocommercially available devices utilizing interstitial fluid (ISF) atthis time, there are active efforts to establish the correlation ofanalytes, such as glucose, in ISF compared to whole blood. If ISF couldbe readily obtained and correlation is established, ISF may bepreferable as a sample since there is no interference of red blood cellsor hematocrit adjustment required.

Another object of the invention is to provide a method which can draw asmall but adjustable sample, i.e. 3 μL for one test device and 8 μL foranother test device, as appropriate.

Another object of this invention is to provide a method by which thedrawn sample is collected and may be easily presented to a testingdevice, regardless of the location of the sample site on the body. Thisapproach helps with infection control in that multiple patients are notbrought in contact with a single test instrument; only the samplingdevice with a disposable patient-contact portion is brought to the testinstrument. Alternatively, the disposable portion of a test device maybe physically coupled with the sampler so the sample can be broughtdirectly into the test device during sampling. The test device may thenbe read in a test instrument if appropriate or the testing system can beintegrated into the sampler and the test device can provide directresults displayed for the patient.

It is a further object of the invention is to provide a device forminimally invasive sampling comprising a reusable sampler and disposablelancet member, and sample collection device.

SUMMARY OF THE INVENTION

One aspect of the present invention involves a lancing device forlancing skin to sample blood or interstitial fluid. The devicecomprising a housing. A lancet carrier is mounted adjacent a front endof the housing for longitudinal movement relative thereto. A cockablespring-biased hammer mechanism is provided for pushing the lancetcarrier forwardly to lance the skin. A latch is provided for releasableretaining the hammer mechanism in a cocked position. A latch-releasingmechanism includes a skin-contacting portion for being rearwardlydisplaced in response to being pressed against the skin, and alatch-releasing portion for releasing the latch in response to therearward displacement of the skin contacting portion.

In another aspect of the invention, a safety mechanism is provided whichis normally disposed in a safety position for preventing the hammermechanism from being cocked, and being movable to a non-safe position inresponse to installation of the lancet carrier into the housing forenabling the hammer mechanism to be cocked.

In another aspect of the invention, a disposable lancet comprises a bodywhich houses a skin lancing member and a capillary tube. A pusher memberis provided for pushing the capillary tube forwardly relative to thebody after the skin has been lanced, for drawing-in fluid from thelanced skin.

Yet another aspect of the invention relates to the combination of adisposable lancet and a carrier therefor. The carrier comprises a sleeveadapted to be mounted in a housing. The sleeve includes an internalsurface forming a through passage extending from an upper end to a lowerend of the sleeve. The disposable lancet is seated in the throughpassage. The internal surface is configured to permit insertion andremoval of the disposable lancet solely through the upper end. Theinternal surface includes at least one upwardly facing shoulder on whichthe disposable lancet is supported. The invention also relates to thelancet carrier per se.

Another aspect of the invention relates to a sampling device forsampling body fluid. The sampling device comprises a housing defining alongitudinal axis, and an incision-forming means for forming an incisionthrough the skin surface. A stimulator member is mounted at a forwardend of the housing and is depressible against the skin to depress a ringof body tissue in surrounding relationship to the skin for urging bodyfluid toward and outwardly through the incision, to form a drop of bodyfluid at an open end of the incision. A pusher member is provided formoving the capillary tube forwardly relative to the carrier fordrawing-in the body fluid.

A method aspect of the invention involves the steps of abutting aforward end of a housing against a skin surface of a user's body, andforming an incision through the skin surface. The housing is pressedagainst the skin surface to repeatedly depress a ring of body tissue insurrounding relationship to the incision to urge body fluid toward andoutwardly through the incision to form a drop of body fluid at an openend of the incision . The capillary tube is extended forwardly relativeto the carrier, and a forward end of the capillary tube is inserted intothe drop of body fluid.

BRIEF DESCRIPTION OF THE DRAWINGS

The objects and advantages of the invention will become apparent fromthe following detailed description of a preferred embodiment thereof inconnection with the accompanying drawing in which like numeralsdesignate like elements and in which:

FIG. 1 is a side elevational view of a lancing device according to thepresent invention;

FIG. 2 is a side elevational view of a disposable being inserted into alancet carrier unit, with the lancet carrier unit being shown inlongitudinal section;

FIGS. 3A-3H are longitudinal sectional views taken through the lancingdevice and depicting the device in various stages of operation;

FIG. 4 is a longitudinal sectional perspective view of the lancingdevice according to the invention;

FIG. 5 is a bottom perspective view of a pusher member according to theinvention;

FIG. 6 is a bottom perspective view of an adapter member according tothe present invention;

FIG. 7 is a bottom perspective view of a hammer member according to thepresent invention;

FIG. 8 is another bottom perspective view of the hammer member depictedin FIG. 7;

FIG. 9 is a perspective view of one-half of the housing part accordingto the present invention;

FIG. 10 is a perspective view of the other housing part according to theinvention;

FIG. 11 is a perspective view of a disposable according to theinvention, with a capillary tube shown in phantom;

FIG. 12 is a bottom perspective view of an interposer member accordingto the present invention;

FIG. 13 is a side elevational view of a disposable carrier memberaccording to the present invention, with projections of a disposableshown in phantom lines when the disposable is in an installed condition;

FIG. 14 is a side elevational view, taken from another angle, of thedisposable carrier shown in FIG. 13;

FIG. 15 is a sectional view taken through the carrier member of FIG. 13;and

FIG. 16 is a bottom perspective view of the carrier of FIG. 13.

DETAILED DESCRIPTION OF A PREFERRED EMBODIMENT OF THE INVENTION

A minimally invasive sampling device 10 shown in FIG. 1, includes atubular housing 12 formed of two half-shells 12A, 12B (see FIGS. 9 and10) that are secured together. The housing 12 defines a longitudinalaxis A and a lower open end 14 adapted to receive a removable lancetcarrier unit 16. That carrier unit serves to carry a disposable lancetmember 150 (hereinafter a "disposable") and to stimulate a skin puncturesite, as will be explained subsequently.

Also mounted in the housing 12 (see FIG. 3A) are a hammer 18 fordisplacing the disposable lancet member downwardly in a skin-piercingdirection, a manual handle 20 for raising the hammer to a cocked (i.e.,downwardly biased) position, an interposer 22 for automaticallyreleasing the hammer in response to a manual pushing of the deviceagainst a skin surface, a manually actuable pusher 24 for pushing ablood-receiving capillary tube downwardly, and a plurality of springsfor achieving proper placement and movement of the above-describedparts.

The interposer 22, shown in FIGS. 3 and 12, is longitudinal movable inthe housing 12 and includes lower and upper cylindrical portions 30, 32,the lower portion being of smaller diameter than the upper portion toform an upwardly facing shoulder 34. A pair of diametrically opposedslits 36 is formed in the lower portion 30 for enabling the carrier unit16 to be slid upwardly into the housing 12.

Formed in the upper portion 32 is a slot 40 through which project threelongitudinally parallel guide ribs 42 (see FIG. 10) that are formedintegrally with the inner surface of the housing shell 12B. A center oneof the ribs 42 is shorter than the other two ribs 42 to form therewith aspace into which an end of a capillary tube 164 can fit, as will beexplained. Spaced ninety degrees from the slot 40 is another slot 44,and formed on a wall of that slot 44 is a triggering protrusion 46having an inclined upper cam surface 47, which serves to release thehammer 18 from a cocked position as will be explained.

A coil compression spring 45 is disposed between an upper end of theinterposer 22 and shoulders 47 formed on the pusher 24 to bias theinterposer 22 downwardly.

The pusher 24, shown in FIG. 5, is longitudinally movable and includes asemi-cylindrical portion 50 having a knob 52 projecting radiallyoutwardly from an upper end thereof. The knob 52 is sized to slide alonga longitudinal slot 53 formed in the housing 12. Projecting radiallyinwardly from a lower end of an inner surface 54 of the portion 50 is alocking rib 56, and an actuating rib 58. The locking rib 56 andactuating rib 58 project radially inwardly through the slot 40 formed inthe interposer 22. The actuating rib 58 extends downwardly between theguide ribs 42 of the body 12, see FIGS. 4 and 11.

The hammer 18, shown in FIGS. 7 and 8, is longitudinally movable in thebody 12, and includes a top wall 70 having an upper opening 72 to enablethe handle 20 to be mounted therein. An upper portion 74 of the hammer18 houses a coil compression spring 76 (see FIG. 3A which serves as arecovery spring acting between the hammer and the handle 20, as will beexplained. The lower portion of the hammer 18, comprises a latching arm82, and a pair of parallel, longitudinal impact legs 80 which straddlethe guide ribs 42 of the body 12. The latching arm 82 is spaced from oneof the legs 80, to accommodate the locking rib 56 therebetween (seeFIGS. 3A and 4). The latching arm 82 includes a radial outward finger 84on its lower end, the top of which is defined by an inclined camfollower surface 86. As will be explained, the latching arm 82 isflexible in a radial direction when the finger 84 travels verticallypast a stop 88 projection which projects radially inwardly from theinner surface of the housing 12 as the hammer is being raised to acocked position (see FIG. 3E).

A coil compression spring 90 acts between an upper wall 92 of the body12 and the top wall 70 of the hammer 18 to bias the hammer downwardly(see FIG. 3A). A coil compression spring 93 surrounding the spring 90acts between the upper wall 92 and an upper edge 94 of the pusher 24 tobias the pusher downwardly.

The carrier unit 16 includes an adapter 100 depicted in FIGS. 2 and 6.The adapter 100 is generally cylindrical and is telescopingly disposedwithin a stimulator sleeve 102. A coil compression spring 104 isinterposed between a lower edge of the adapter 100 and an annular flange106 projecting radially inwardly from an inner surface of the sleeve102. The adapter 100 includes a plurality of longitudinal slots 107dividing the adaptor into a plurality of spring fingers 108, two ofwhich have a circumferential groove 110 formed in an upper portionthereof. The grooves are configured to receive projections 112 which areformed integrally on inner surfaces of the housing shells 12A, 12B, inorder to releasable secure the adapter within the housing 12. That is,if a downward force is applied to the adapter, the spring fingers 108will yield and permit the adapter to be removed from the housing 12.

The adapter 100 also includes three radially outwardly projecting keys113 arranged to engage respective sides 114 of protrusions 115 formed oninner surfaces of the housing shells 12A, 12B. The keys 113 and sides114 are oriented such that the adapter can only enter the housing 12 inone specific circumferential orientation. A longitudinal keyway 117 isformed in an inner surface of the adapter for reasons to be explained.

Telescopingly mounted within the sleeve 102 is an inner ring 116 havinga radially outwardly projecting shoulder 118 near its lower end, and aradially inwardly projecting shoulder 120 formed near its upper end. Theshoulder 118 is arranged to abut a lower end of the flange 106. The ring116 includes an annular recess which receives a radial projection of theadapter 100 to form a snap-in connection 117 therebetween (see FIG. 2).

Situated coaxially within the adapter 100 and ring 116 is a lancetcarrier 130 which is also depicted in FIGS. 13-16. The lancet carrier130 is generally in the form of a cylindrical sleeve which includes avertical through-passage 131 to enable a disposable lancet member 150 tobe inserted downwardly thereinto when the carrier unit 16 has beenremoved from the housing 12. A coil compression spring 132 acts betweena radial outer flange 134 of the lancet carrier 130 and radially innershoulder 120 formed on the ring 116.

The lancet carrier includes a pair of downwardly inclined, upwardlyfacing guide ramps 140 formed on its inner surface for guiding thedisposable lancet member. Lower ends of the guide ramps 140 intersect toform an upwardly open recess 142. The ramps and recess form an upwardlyfacing seat on which the disposable lancet member is supported. Aradially outwardly projecting key 133 is formed on an upper annularflange 135 of the carrier 130. That key 133 enters the keyway 117 if theadapter 100 to orient the carrier 130 circumferentially relative to theadapter.

The disposable lancet member 150 is depicted in FIGS. 2 and 11 andincludes a generally cylindrical body 152 having a needle 154 projectingfrom its lower end. Projecting radially outwardly from an outerperiphery of the disposable lancet member 150 are three bosses 156spaced circumferentially and longitudinally apart. That is, there areprovided a lower boss 156, and a pair of upper bosses 158 disposed atthe same elevation above the lower boss. The three bosses are spacedcircumferentially apart from one another as the disposable lancet memberis viewed in a longitudinal direction. When the disposable lancet memberis dropped downwardly into an upper end of the lancet carrier 130 (seeFIG. 2), the two upper projections engage respective ones of the twoguide ramps 140 to guide downward motion of the disposable lancet memberand ensure that the lower boss 156 enters the recess 142 (see also FIG.13).

The disposable lancet member 150 further includes a slot 160 extendinglongitudinally therealong. Disposed within the slot 160 are plurality ofpairs of opposed holding fingers 162 which are configured tofrictionally grip the capillary tube 164 and retain the tube 164 in anorientation parallel to the longitudinal axis of the disposable lancetmember, as shown in broken lines in FIG. 11. Due to the cooperationbetween the projections 156, 158 of the disposable lancet member and theguide ramps 140 of the lancet carrier 130, the capillary tube will bepositioned in axial alignment with the actuating finger 58 of the pusher24 when the unit 16 is inserted into the housing 12, for reasons to beexplained.

The handle 20 (FIGS. 3A and 4) includes a pair of longitudinallyextending lift fingers 170 which project downwardly through the top wall70 of the hammer 18. Lower ends of the lift fingers constitute radiallyoutwardly projecting feet 172 against which the lower end of the spring76 bears. A manually grippable knob 174 is disposed at the top of thehandle to enable a riser to raise the handle.

To explain the operation of the lancing device 10, attention isinitially directed to FIG. 3A which depicts the device 10 in a conditionwhere no disposable lancet member 150 is mounted in the carrier unit 16.To install a disposable lancet member the carrier unit 16 is pulleddownwardly from the housing, and a disposable lancet member 150 isdropped downwardly into the carrier 130 (see FIG. 2). In so doing, thebosses 156, 158 of the disposable lancet member ride along the guideramps 140 of the lancet carrier until the lower boss 156 comes to restin recess recess 142 of the carrier. As a result, the capillary tube 164of the disposable lancet member is oriented in a specific relationshipwith respect to the unit 16.

The unit 16 is then pushed longitudinally upwardly into the front end ofthe housing 12 until the grooves 110 formed in the spring fingers 108 ofthe adapter 100 snap onto the projections 112 of the housing 12, therebylocking the unit 16 in place (see FIG. 3B). Due to the relationshipbetween the keys 113 on the adapter, and the sides 115 of theprojections 114 formed on the housing 12, the adapter can be inserted inonly one circumferential (rotary) relationship relative to the housing12. Furthermore, since the circumferential relationship between thelancet holder 130 and the adapter 100 is pre-set by the engagementbetween the key 133 on the holder 130 and the keyway 117 on the adapter,it is ensured that the upper end of the capillary tube 164 is alignedwith the actuating finger 58 of the pusher 24. Since the upper end ofthe capillary tube projects slightly upwardly past the upper end of thedisposable lancet member 150 (see FIG. 3B), it pushes the actuatingfinger 58, and thus the entire pusher 24, slightly upwardly. In sodoing, the locking rib 56 of the pusher is raised to a level above thestop 88 of the housing 12 for a reason which will become apparent.

If a protection sheath S covers the needle 154 (see FIG. 2), it can bepulled off by the user who then grasps the knob 174 of the handle 20 andpulls upwardly thereon (FIG. 3C). This causes the spring 76 to becompressed between the feet 172 of the raising fingers 170 on the onehand, and the top wall 70 of the hammer 18. When the spring 76 bottomsout, further raising of the handle 20 causes the hammer 18 to be raised.Accordingly, the inclined surface 86 on the top of the latching finger84 sequentially engages the undersides of the triggering protrusion 46and the stop 88, causing the latching arm 82 to be flexed radiallyinwardly and allowing the finger 84 to pass over the protrusion 46 andthen over the stop 88. Eventually, the finger 84 travels past the stop88 and snaps radially outwardly, whereby downward movement of the finger(and thus of the hammer) is prevented by the top of the stop 88 (FIG.3C).

It will be appreciated that had the locking rib 56 not been previouslyraised, the latching finger could not have been flexed radiallyinwardly. Therefore, the locking rib 56 ensures that the hammer 18cannot be placed in an armed or cocked position unless a disposable 150has been installed.

As the hammer 18 was raised, the spring 90 was simultaneouslycompressed, so now the hammer 18 is biased downwardly thereby.

When the handle 20 is released, the spring 76 pushes it downwardly (seeFIG. 3D) until the feet 172 of the handle come to rest against aradially inwardly projecting shoulder 180 of the now-raised handle 18,whereby the knob 174 remains slightly raised by a distance D withrespect to its previous position, serving as a visual indication thatthe hammer is cocked (armed).

When the stimulating sleeve 102 is pushed downwardly against the user'sskin (FIG. 3E), the sleeve 102 becomes displaced upwardly against thebias of the spring 104, and raises the interposer 22 and its triggeringprotrusion 46 against the bias of spring 45. The triggering protrusion46 is circumferentially offset with respect to the stop 88, so theprotrusion is able to contact the underside of the latching finger 84and cam it radially inwardly off the stop 88. This enables thepreviously-compressed spring 90 to displace the hammer 18 and its impactlegs 80 downwardly opposite the bias of the spring 76 and against thedisposable lancet member 150 (FIG. 3F), to push the disposable lancermember 150 and the carrier 130 downwardly opposite the bias of thespring 132, whereby the needle lances the skin. The carrier 130 and thedisposable lancet member 150 are immediately withdrawn upwardly by theaction of the spring 132. Such withdrawal is possible since the hammer18 was immediately retracted by the spring 76. Thus, the lancing andretraction of the lancet is performed as a substantially continuousmotion.

Next, the user repeatedly reciprocates the housing 12 up and down,whereby the stimulating sleeve 102 remains in contact with the skin butrepeatedly pressured by the spring 45 and repeatedly opens and closesthe wound in a manner pumping fluid (such as blood) to the skin surfacein the manner described in greater detail in Application Ser. No.08/858,043 (attorney docket 018176-060), the disclosure of which isincorporated by reference herein.

That is, each time that a downward force is applied, the end face of theouter stimulating sleeve exerts a downward force which depresses aring-shaped portion of the skin and body tissue which is disposed insurrounding relationship to the wound or incision I, causing the woundedarea to bulge while pulling apart the sides of the wound. Hence, fluidsuch as blood or interstitial fluid is trapped and pressurized so thatit travels upwardly through the pulled-open end of the bulging woundsince the surrounding ring of depressed skin and body tissue restrictsthe outward flow of fluid.

When the downward force is released, the sides of the wound close, andfresh fluid flows toward the area of the wound to replace fluid whichhad been forced upwardly through the wound. As the downward force isreapplied, the above-described action is repeated and additional fluidis forced through the wound. Eventually, this "pumping" action resultsin the formation of a suitably large drop B of body fluid.

Although the end face of the sleeve 102 is disclosed as being generallyannular, it could be of other configuration such as oval or polygonal,whereby the ring of depressed body tissue would be similarly configured.

When a sufficiently large drop of fluid B has been developed at the skinsurface (FIG. 3G), the user applies a downward force F to the knob 52 ofthe pusher 24 to displace the pusher and its actuating rib 58 downwardlyagainst the bias of the spring 38. This pushes the capillary tube 164downwardly until the lower end thereof projects from the bottom of thehousing 12. At that point, the lower end of the capillary tube is placedin the drop of blood to draw blood thereinto by capillary action. Thepusher 24 can be released, whereupon it will be displaced upwardly bythe spring 38.

Then, a strip of material 200 can be brought into contact with bottom ofthe capillary tube (FIG. 3H) to draw-out the fluid sample for analysis.

To perform a subsequent lancing/sampling operation, the user grasps thesleeve 102 and pulls out the carrier unit 16. The disposable lancetmember 150 can then be lifted from the carrier 130 and discarded,whereupon a new disposable lancet member can be inserted.

Except for the needle 154 and the springs 93, 90, 45, 76, 104 and 132,the parts of the lancing device 10 are preferably formed of plastic.

It will be appreciated that the device 10 provides for an automatictriggering of the hammer in response to a pressing of the device againstthe skin. This eliminates any tendency for the user to jerk the deviceupwardly at the instant of triggering and ensures that penetrations ofconstant depth will be performed from one lancing operation to the next.

The ability of the device to prevent the hammer from being cocked unlessa disposable lancet member has been installed provides assurance thatthe disposable lancet member will not be accidentally displacedforwardly as the carrier unit is being installed, as could otherwiseoccur if the hammer were in a cocked state during such installation.Hence, the user is protected against an accidental wounding.

The ability of the device to push-out the capillary tube for talking-ina fluid sample simplifies the sampling operation and minimizes theamount of direct manual handling of the capillary tube which isrequired. In fact, no direct contact with that tube need occur whenusing the device. This feature of the invention does not require the useof a lancet for making the incision. In lieu of using a lancet to makean incision, known pneumatic or hydraulic injectors of the type whichinject pressurized gas or liquid against the skin could be used. Suchauto injectors are sold by Becton-Dickinson, for example, to injectinsulin. By eliminating the insulin and merely injecting the gas (e.g.,air or nitrogen) or liquid (e.g., water) at pressures above 30 psi. anincision could be formed in the skin for taking samples of body fluid.Advantageously, small particles could be mixed with the gas to promotethe tissue-cutting action. The particles could comprise carbon particlesof from 1 micron to 0.010 inches in diameter.

The ability to load and unload a disposable lancet member into thecarrier unit through an upper end of that unit means that the user cankeep his/her hands remote from the needle. This ensures againstaccidental wounding, possibly by a contaminated needle. The three-pointsecurement of the disposable lancet member within the carrier, asdefined by the three projections of the disposable, creates a stablemovement-free mounting of the disposable lancet member within thecarrier unit. Hence, the disposable lancet member will not tend to movelaterally during a lancing procedure, thereby reducing recess amount ofpain that may be experienced by the user.

Also, as explained in concurrently filed application Ser. No. 08/858,043(attorney docket 018176-060), the ability of the device to pump bodyfluids such as blood or interstitial fluid to the skin surface enablesthe device to be used to lance the skin at areas of the body which areless susceptible to pain, such as the arm for example.

Although the present invention has been described in connection with apreferred embodiment thereof, it will be appreciated by those skilled inthe art that additions, modifications, substitutions and deletions notspecifically described may be made without departing from the spirit andscope of the invention as defined in the appended claims.

What is claimed is:
 1. A lancing device for lancing the skin to sample blood or interstitial fluid, comprising:a housing; a lancet carrier carrying disposable lancet member, the disposable lancet member includes a body holding a skin lancing member, a capillary tube, and a pusher member for pushing the capillary tube forward relative to the carrier for drawing-in fluid from the lanced skin, the carrier mounted adjacent a front end of the housing for movement relative thereto; a cockable spring-biased hammer mechanism for displacing the lancet carrier forwardly to lance the skin; a latch for releasably retaining the hammer mechanism in a cocked position; and a latch-releasing mechanism including a skin-containing portion for being rearwardly displaced in response to being pressed against the skin, and a latch-releasing portion for releasing the latch in response to the rearward displacement of the skin-contacting portion.
 2. The lancing device according to claim 1 wherein the skin-contacting portion comprises a sleeve mounted at the front end of the housing, the sleeve being spring-biased forwardly and being displaceable rearwardly in response to being pressed against the skin, to cause the latch-releasing portion to release the latch.
 3. The lancing device according to claim 1, further comprising a safety device normally disposed in a safety position for preventing the hammer mechanism from being cocked, and being movable to a non-safety position in response to installation of the lancet carrier into the housing for enabling the hammer mechanism to be cocked.
 4. The lancing device according to claim 3, wherein the safety device is moved to its non-safety position by an upper end of the capillary tube within the lancet carrier.
 5. The lancing device according to claim 4, wherein the lancet carrier comprises a sleeve mounted in the housing; the sleeve including an internal surface forming a through-passage extending from an upper end to a lower end of the sleeve; a disposable lancet seated in the through-passage; the internal surface configured to permit insertion and removal of the disposable lancet solely through the upper end; the internal surface including at least one upwardly facing seat on which the disposable lancet is supported.
 6. The lancing device according to claim 3, wherein the lancet carrier comprises a sleeve mounted in the housing; the sleeve including an internal surface forming a through-passage extending from an upper end to a lower end of the sleeve; a disposable lancet seated in the through-passage; the internal surface configured to permit insertion and removal of the disposable lancet solely through the upper end; the internal surface including at least one upwardly facing seat on which the disposable lancet is supported.
 7. The lancet device according to claim 1, wherein the lancet carrier comprises a sleeve mounted in the housing; the sleeve including an internal surface forming a through-passage extending from an upper end to a lower end of the sleeve; a disposable lancet seated in the through-passage; the internal surface configured to permit insertion and removal of the disposable lancet solely through the upper end; the internal surface including at least one upwardly facing seat on which the disposable lancet supported.
 8. The lancing device according to claim 1 wherein the skin contacting portion includes a sleeve structure mounted for repeated rearward displacements to urge body fluid from lanced skin.
 9. The lancing device according to claim 8 wherein the skin contacting portion is shaped to form a depressed ring of body tissue in surrounding relationship to an incision formed in the skin.
 10. The lancing device according to claim 9, further including a safety device normally disposed in a safety position for preventing the hammer mechanism from being cocked, and being movable to a non-safety position in response to installation of the lancet carrier into the housing for enabling the hammer mechanism to be cocked.
 11. A lancing device for lancing skin to sample blood or interstitial fluid, comprising:a housing; a lancet carrier carrying a disposable lancet member, the disposable lancet member includes a body holding a skin lancing member, a capillary tube, and a pusher member for pushing the capillary tube forward relative to the carrier for drawing-in fluid from the lanced skin, the carrier installable into a front end of the housing and being movable relative thereto; a cockable spring-biased hammer mechanism for displacing the lancet carrier forwardly to lance the skin; a latch-releasing mechanism for releasing a latch; and a safety device normally disposed in a safety position for preventing the hammer mechanism from being cocked, and being movable to a non-safety position in response to installation of the lancet carrier into the housing for enabling the hammer mechanism to be cocked.
 12. The lancing device according to claim 11, wherein the lancet carrier comprises a sleeve mounted in the housing; the sleeve including an internal surface forming a through-passage extending from an upper end to a lower end of the sleeve; a disposable lancet seated in the through-passage; the internal surface configured to permit insertion and removal of the disposable lancet solely through the upper end; the internal surface including at least one upwardly facing seat on which the disposable lancet is supported.
 13. A lancing device for lancing skin to sample blood or interstitial fluid, comprising:a housing; a carrier carrying a disposable lancet member, the disposable lancet member including a body having a skin-lancing member and a capillary tube; a spring-biased hammer for pushing the carrier so that the lancet lances the skin; and a pusher member for pushing the capillary tube forwardly relative to the carrier for drawing-in fluid from lanced skin.
 14. The lancing device according to claim 13, wherein the carrier comprises a sleeve mounted in the housing; the sleeve including an internal surface forming a through-passage extending from an upper end to a lower end of the sleeve; the internal surface configured to permit insertion and removal of the disposable lancet solely through the upper end; the internal surface including at least one upwardly facing seat on which the disposable lancet is supported.
 15. A lancet carrier adapted to carry a disposable lancet, the lancet carrier comprising a sleeve to be mounted in a housing, the sleeve including an internal surface forming a through-passage extending from an upper end to a lower end of the sleeve and configured to permit insertion and removal of a disposable lancet solely through the upper end, the internal including an upwardly facing seat adapted to support a disposable lancet, the seat includes a plurality of upwardly facing shoulders having a pair of downwardly inclined ramps and a slot disposed below the ramps, the lancet including vertically spaced projections extending outwardly therefrom and bearing against respective ones of the upwardly facing shoulders.
 16. A sampling device for sampling body fluid, comprising:a housing defining a longitudinal axis; incision-forming means mounted in the housing for forming an incision through a skin surface; a stimulator member mounted at a forward end of the housing and being depressible against the skin to depress a ring of body tissue in surrounding relationship to the skin for urging body fluid toward and outwardly through the incision to form a drop of body fluid at an open end of the incision; a capillary tube; and a pusher member for moving the capillary tube forwardly within the housing for drawing-in the body fluid.
 17. The lancing device according to claim 16 wherein the incision forming means comprises:a lancet carrier carrying a disposable lancet, the lancet including a skin-lancing member and a capillary tube, the lancet carrier mounted adjacent a front end of the housing for longitudinal movement relative thereto; and means for driving the lancet carrier forwardly and then rearwardly in a substantially continuous motion to form an incision through the skin surface and retract the lancet from the incision.
 18. The lancing device according to claim 17, further including a cockable spring biased hammer mechanism in the housing for displacing the lancet carrier forwardly; and a safety device disposed in the housing normally in a safety position for preventing the hammer mechanism from being cocked, and being movable to a non-safety position by a rear end of the capillary tube.
 19. A method of taking a sample of body fluid, comprising the steps of:A) abutting a forward end of a housing against a skin surface of a user's body; B) forming an incision through the skin surface; C) pressing the housing against the skin surface a plurality of times to repeatedly depress a ring of body tissue in surrounding relationship to the incision to urge body fluid toward and outwardly through the incision to form a drop of body fluid at an open end of the incision; D) extending the capillary tube forwardly relative to the carrier; and E) inserting a forward end of the capillary tube into the drop of body fluid to draw-in the body fluid.
 20. The method according to claim 19 wherein step A comprises abutting the housing against a surface of the user's body other than a finger tip thereof.
 21. The method according to claim 19 wherein step A comprises abutting the housing against the user's forearm. 